Panelboard with mounting block securing stab contacts

ABSTRACT

The invention contemplates an electrical load center construction wherein specially formed cavities and recesses accommodate slidable insertion and captive retention of (a) a neutral-bar assembly, and (b) a multiple-contact conductor assembly. Captive retention is secured upon clamping the mounting face of the block to a base panel. The particular arrangement of through-openings for inserted reception of various areas of the conductor assembly affords selective accommodation of one or more of a variety of possible conductor assemblies, depending upon the desired application and use of the load center.

United States Patent 1 Kobryner [451 Sept. 4, 1973 PANELBOARD WITHMOUNTING BLOCK SECURING STAB-CONTACTS [75] Inventor: Herman H. Kobryner,Forest Hills,

[73] Assignee: Arrow-Hart, lnc., Hartford, Conn.

[22] Filed: Oct. 2, 1972 [21] Appl. No.: 294,092

[52] US. Cl. 317/119, 339/198 N [51] Int. Cl. 1102b 1/04 [58] Field ofSearch 317/119; 339/198 R, 339/198 N [56] References Cited UNITED STATESPATENTS 3,312,874 4/1967 Stanback 317/119 3,668,591 6/1972 Kobryner....339/198 N 3,155,445 11/1964 Johnson .[317/119 Primary ExaminerJ. V.Truhe Assistant ExaminerGerald P. Tolin Attorney- Nichol M. Sandoe, RoyC. Hopgood et a1.

[ 57] ABSTRACT The invention contemplates an electrical load centerconstruction wherein specially formed cavities and recesses accommodateslidable insertion and captive retention of (a) a neutral-bar assembly,and (b) a multiple-contact conductor assembly. Captive retention issecured upon clamping the mounting face of the block to a base panel.The particular arrangement of throughopenings for inserted reception ofvarious areas of the conductor assembly affords selective accommodationof one or more of a variety of possible conductor assemblies, dependingupon the desired application and use of the load center.

11 Claims, 12 Drawing Figures PANELBOARD WITH MOUNTING BLOCK SECURINGSTAB-CONTACTS The invention relates to the construction of an electricalload center, suitable for direct mounting on a plate or panel, or on thebase of a suitable box enclosure.

It is an object of the invention to provide an improved construction ofthe character indicated, particularly adapted for use in mobile homesand recreational housing, where the need does not exist for greatnumbers of circuits.

Another object is to meet the above object with a constructioninherently lending itself to acceptance of conventional self-containedstab-mounted circuitbreaker modules.

A further object is to provide such a load center of basic design,lending itself to varied applications depending upon selection ofparticular alternative connector parts.

It is also an object to provide such a construction employing unjointedconnectors and serving plural circuits.

It is a general object to achieve the above objects with basicallysimple, inexpensive and foolproof structure, without sacrifice ofdesirable electrical properties.

Other objects and various further features of novelty and invention willbe pointed out or will occur to those skilled in the art from a readingof the following specification in conjunction with the accompanyingdrawings. In said drawings, which show, for illustrative purposes only,preferred forms of the invention:

FIG. 1 is a plan view of a boxmounted load center of the invention;

FIG. 2 is a perspective view of a removable mounting-block part of thestructure of FIG. 1, shown in exploded relation with another part priorto a preassembly operation;

FIG. 3 is another perspective view of the mountingblock part of FIG. 1,shown in exploded relation with a further part prior to a preassemblyoperation;

FIGS. 4, 5 and 6 are, respectively, plan rear and bottom views of themounting-block part of FIG. 1;

FIG. 7 is a sectional view at 77 in FIG. 4;

FIGS. 8 and 9 are perspective views of different conductor elements,available as alternates for the preassembly suggested in FIG. 3; and

FIGS. 10, 11 and 12 are simplified plan views showing variousselectively available applications of the invention.

In FIG. 1, the invention is shown in application to a rectangular loadcenter box 10 having a base panel or plate 11 and upstanding sides, andbeing selectively closed by a cover 12 secured by means 13. Box 10 andits cover 12 may be of formed sheet steel, as is conventional, the cover12 having a cut-out or opening 14 appropriate to the number and size ofstab-mounted circuit-breaker modules 15-16 within the load center.

To accommodate the circuit-breaker modules, a plate 17, formed withplural laterally spaced struck-up tabs 18, is secured as by screws 19 tothe base panel 11. The heel ends of the module bases engage under thesetabs 18, as appropriate and conventional, while the contact ends arepressed into upstanding stabs 20-20 forming part of a mounting assembly21 of the invention.

The mounting assembly 21 comprises a mounting block 22 of insulatingmaterial and is made as a single injection-molded part of suitableplastic, such as the mica-filled polyethylene material commerciallyavailable from General Electric Company and known under the mark Noryl";additional reference is made to FIGS. 2 to 7 in connection with theblock 22. To complete the description of box 10 and its contents, theusual grounding connections are provided by a terminal block 23 securedto a side wall of the box, and a bonding jumper 24 may be provided tobond the neutral to the box. The particular electrical arrangement shownin FIG. 1 provides for a three-wire single-phase system, wherein the twohot leads are connected at terminals 25-25', electrically connected tothe stabs 20-20, respectively, for the distribution circuit breakers15-16. The neutral connection for the supply conductor may be made atthe large terminal 26 of a neutral-bar connector 27, forming part of theassembly 21.

The mounting block 22 is so devised with retaining cavities that itentraps all conductive members between itself and a flat insulationplate member or sheet 28. The entire assembly is compressionally securedto the back panel 11 of the box by screws 29 which pass through alignedholes in the mounting block and insulation plate and which engage tappedholes in panel 11.

Referring now to FIGS. 2 to 7, and in particular to FIG. 2, the mountingblock 22 is seen to comprise an upstanding body portion 30, rising froman integral base-flange portion 31; the underside of flange and bodyportions will be understood to be in a common mounting plane or surface,to be compressed against insulating sheet 28, upon assembly to panel 11.The aspect of FIG. 2 reveals accommodation for the neutralbar assembly27, the same being received in a bottomopening cavity 32 upon upwardinsertion, as suggested by light-phantom projection lines for comeralignments of the prismatic body of the neutral assembly 27. Integralledges or cleats 33-34-35 provide stops and guides for retention of theinserted assembly 27, when the bottom surface thereof is in substantialregistry with the mounting-surface plane of the mounting block 22, andsubstantial side-access and top-access windows communicate with cavity32, to provide all necessary neutral clamping and wiring connections tothe bar 27, without disturbing the assembled relation to the box 10.Substantial body mass is devoted to the centrally located alignments 29'for the mounting bolts 29 and to a body bridge 36 between thesealignments. The mounting-body portion 30 is essentially limited toaccommodation of the neutral-bar assembly 27 and bridge 36, leaving asubstantial area of the flange portin 31 accomodation of stab and otherconnector elements, as will more clearly appear from FIG. 3.

In FIG. 3, plural spaced connector openings 37-3- 8-39-40 are seen to beprovided along a single alignment within flange portion 31, and a singledownwardly open channel alignment interconnects lower regions of theseopenings; the net result is provision of integral conductor-retainingbridges 41-42-43 between the respective adjacent pairs of openings.Spacing and size of the openings are selected for the particular staband circuit-breaker geometry for the intended application. As shown inFIG. 3, the single conductor element 44 comprises two arms 25-20,extending upwardly from an integral base or yoke 45. The spacing betweenand shape of openings 37-38 are such as to receive and accurately locatethe respective arms 25-20, and the channel depth beneath bridges41-42-43 is such as to accommodate the thickness of base 45, uponconnector assembly to flange portion 31, at 37-38, all as will beunderstood from the light-phantom projection lines in FIG. 3 for cornersof connector 45; the base 45 is thus insertably received at flangeportion 31, substantially flush with the mounting surface plane of block22. It will be further understood that for the FIG. 1 arrangementwherein breakers 15-16 serve the respective hot sides of a three-wiresingle-phase system, the conductor element 44 serves one side viaopenings 37-38, while a second conductor element 44 (not shown in FIG.3) serves the other side at projecting arm locations 20'-25 via openings39-40. Buttress or shield elements 46, integrally formed with adjacentparts of the flange and body portions 30-31, between adjacent openings37-38-39-40, strengthens the retention of conductor elements by addingto the rigidity of the otherwise thin and flexible flange 31.

FIGS. 8 and 9 illustrate other forms of conductor element, usuable inplace of element 44, for diflerent application situations. For example,the element 50 of FIG. 8 provides a simple integral connection 51between two spaced stab arms 52-53, the connection 51 being centrallygrooved at 54 for accurate fit to one of the bridges in the flangeportion 31, as at the central bridge 42, for the situation depicted inFIG. 10. FIG. 10 may be considered illustrative of application to atwowire single-phase system having provision for a main breaker, forvexample at stab 53, and for a duplex breaker at stab 52; thus providingseparate protection for two branch circuits, in addition to mainprotection; still further, the main breaker could be a duplex breakerhaving one half at high rating, for the mainbreaker function, and theother half low-rated for branch-line protection.

The conductor element 55 of FIG. 9 resembles that of FIG. 8, except thatit provides three spaced upstanding stab arms 56-57-58, integrallyjoined by a base 59, and suitably contoured for removable insertionthrough a succession of three of the flange openings. Such anapplication is depicted in FIG. 11, where more branchcircuit connectionsmay be made in a two-wire singlephase system. For example, the mainbreaker may be connected to stab 58, and duplex breakers at stabs 56 and57 would provide protection for four branch circuits.

The arrangement of FIG. 12 illustrates application of the circuit optionof FIG. 1 to a plate-mounted installation, wherein a base plate 60 issecured by means 61 to raised bumps or pedestals offsetting plate 60from the base panel of a deeper load center box (not shown), as may benecessitated by the larger conduit diameter involved in employing theinvention in larger-current rated installations. Again, however,mounting assembly 21 is secured by means 29 to the insulation sheet 28and plate 60, and the latter is positioned to accommodate breakermodules (e.g., -16) with their exposed faces at the plane of the coverplate (12), as will be understood. I

The described invention will be seen to have achieved all statedobjects. Parts are efficiently captivated upon assembly of block 22 toits panel 11 (60) and insulation sheet 28. Manufacturing economies arerealized by reducing to a minimum the number and complexity of partsspecially needed for different applications. Good electrical propertiesflow from use of unjointed conductors, and conductor elements as at 50and 55 lend themselves to economical manufacture, as by sawing fromextruded channel stock, to desired element width W.

As an illustration of the varied application and use of theinvention,precisely the same block structure 21 will be seen to selectively servedevices of two different current ratings, for example, 40 amp. and amp.,calling for No. 6 (AL) and No. 2 (AL) wire sizes, respectively, in turncalling for conduits of such different size as to employ the shallow-boxarrangement of FIG. 1 for a 40-amp. installation, and the offset-plate,deeper-box arrangement of FIG. 12 for a 70-amp. installation. The sameflexible adaptation feature characterizes stab accommodation by the sameblock 21; for example, if the drawings are viewed as showing stabelements 44-5- 0-55 of the relatively narrow width W involved in a 40-amp. installation, then the widened-notch character of the openings37-38-39-40 will be seen to accommodate stab elements of the greaterwidth and larger wireclamping terminal involved in a 70-amp.installation.

While the invention has been shown and described in detail for thepreferred forms shown, it will be understood that modifications may bemade without departure from the invention.

What is claimed is:

1. An electrical load center, comprising a metal panel plate, a mountingblock of insulating material and having a main body and a mounting face,a sheet of insulating material between said plate and face, and meanscompressionally securing the mounting face of said block to said platewith said sheet therebetween, a generally rectangularly prismaticneutral bar, said block body having a neutral-bar recess open to saidmounting face and being adapted to insertably receive said neutral barvia said mounting, face the effective depth of said recess being lessthan the total height of said block body and adapted to limitneutral-bar insertion at an assembled position when the bottom face ofsaid neutral bar is substantially in register with the plane of saidmounting face, said neutral bar having a conductor port on a transverseaxis between top and bottom faces of said bar, a clamp screw havingthreaded access to said port via the top face of said bar, the barrecess of said mounting block being sufficiently open above said topface and along one lateral side of said bar to provide conductor accessdirect to said port and clampcontrol access to said screw, said mountingblock integrally including a flange contiguous to said main body andhaving a bottom face in common with said mounting face, said flangehaving a plurality of spaced through openings with a channel of limiteddepth interconnecting adjacent of said through openings at the plane ofsaid mounting face, and a unitary conductor element comprising twoupstanding arms connected by a bridge at the base ends thereof, saidarms projecting through adjacent flange openings and upwardly of saidflange, and said bridge fitting said channel to a limited depth suchthat the bottom surface of said bridge is assembled substantially inregister with the plane of said mounting face, whereby upon suchsecuring of said mounting block to said plate, said neutral bar and saidconductor element are captively retained and located with fullneutral-connection access and with said conductive arms projecting forlive-connection access.

2. The load center of claim 1, in which said upstanding an'ns arecircuit-breaker stabs.

3. The load center of claim 1, in which one of said upstanding arms is acircuit-breaker stab and the other of said arms includes live conductorclamp means.

4. The load center of claim 1, in which the plurality of spaced flangethrough-openings is at least three, and in which said unitary conductorelement comprises three similarly spaced upstanding arms bridgeconnectedat their base ends.

5. The load center of claim 4, in which at least two adjacent of saidarms are circuit-breaker stabs.

6. The load center of claim 4, in which all three of said arms arecircuit-breaker stabs.

7. The load center of claim 1, in which said mounting block includes abrace interposed between said through-openings, said brace beingintegrally connected to said flange and the adjacent lateral wall ofsaid main body.

8. The load center of claim 7, in which said plurality of flangethrough-openings is at least three, and in which said brace is one of aplurality providing braced protection between all adjacentthrough-openings.

9. The load center of claim I, in which said securing means comprisesspaced bolts through aligned openings in said mounting block and sheetand plate.

10. The load center of claim 1, in which said plate is the base panel ofa load-center box encasing said sheet and mounting block.

11. The load center of claim 1, in which said plate includes a circuitbreaker mounting tab offset from said mounting block and at standardcircuit-breaker stab spacing from one of said through-openings.

1. An electrical load center, comprising a metal panel plate, a mountingblock of insulating material and having a main body and a mounting face,a sheet of insulating material between said plate and face, and meanscompressionally securing the mounting face of said block to said platewith said sheet therebetween, a generally rectangularly prismaticneutral bar, said block body having a neutral-bar recess open to saidmounting face and being adapted to insertably receive said neutral barvia said mounting, face the effective depth of said recess being lessthan the total height of said block body and adapted to limitneutral-bar insertion at an assembled position when the bottom face ofsaid neutral bar is substantially in register with the plane of saidmounting face, said neutral bar having a conductor port on a transverseaxis between top and bottom faces of said bar, a clamp screw havingthreaded access to said port via the top face of said bar, the barrecess of said mounting block being sufficiently open above said topface and along one lateral side of said bar to provide conductor accessdirect to said port and clamp-control access to said screw, saidmounting block integrally including a flange contiguous to said mainbody and having a bottom face in common with said mounting face, saidflange having a plurality of spaced through openings with a channel oflimited depth interconnecting adjacent of said through openings at theplane of said mounting face, and a unitary conductor element comprisingtwo upstanding arms connected by a bridge at the base ends thereof, saidarms projecting through adjacent flange openings and upwardly of saidflange, and said bridge fitting said channel to a limited depth suchthat the bottom surface of said bridge is assembled substantially inregister with the plane of said mounting face, whereby upon suchsecuring of said mounting block to said plate, said neutral bar and saidconductor element are captively retained and located with fullneutral-connection access and with said conductive arms projecting forlive-connection access.
 2. The load center of claim 1, in which saidupstanding arms are circuit-breaker stabs.
 3. The load center of claim1, in which one of said upstanding arms is a circuit-breaker stab andthe other of said arms includes live-conductor clamp means.
 4. The loadcenter of claim 1, in which the plurality of spaced flangethrough-openings is at least three, and in which said unitary conductorelement comprises three similarly spaced upstanding armsbridge-connected at their base ends.
 5. The load center of claim 4, inwhich at least two adjacent of said arms are circuit-breaker stabs. 6.The load center of claim 4, in which all three of said arms arecircuit-breaker stabs.
 7. The load center of claim 1, in which saidmounting block includes a brace interposed between saidthrough-openings, said brace being integrally connected to said flangeand the adjacent lateral wall of said main body.
 8. The load center ofclaim 7, in which said plurality of flange through-openings is at leastthree, and in which said brace is one of a plurality providing bracedprotection between all adjacent through-openings.
 9. The load center ofclaim 1, in which said securing means comprises spaced bolts thrOughaligned openings in said mounting block and sheet and plate.
 10. Theload center of claim 1, in which said plate is the base panel of aload-center box encasing said sheet and mounting block.
 11. The loadcenter of claim 1, in which said plate includes a circuit breakermounting tab offset from said mounting block and at standardcircuit-breaker stab spacing from one of said through-openings.